| go for broke(expression, adjective, idiom, severe, honest) |
| grim(adjective, harsh, cruel, determined, fierce) |
| hang-tough(adjective, harsh, cruel, determined, fierce) |
| hang in(expression, adjective, harsh, cruel, determined) |
| hanging tough(expression, adjective, determined, vigorous, resolute) |
| hard(adjective, harsh, cruel, determined, fierce) |
| hard-headed(adjective, persistent, constant, pitiless, unyielding) |
| harsh(adjective, cruel, determined, fierce, persistent) |
| humorless |
| immovable |
| implacable(adjective, harsh, cruel, determined, fierce) |
| in for long haul |
| incessant(adjective, determined, steady, resolute, persistent) |
| indefatigable(adjective, untiring) |
| inexorable(adjective, harsh, cruel, determined, fierce) |
| inflexible(adjective, harsh, cruel, determined, fierce) |
| inhuman(adjective, harsh, cruel, determined, fierce) |
| insistent |
| intent(adjective, serious) |
| intransigent(adjective, persistent, constant, pitiless, unyielding) |